태생 및 수유기에 에틸알코올에 노출된 흰쥐의 소뇌피질에 관한 전자현미경적 연구

임신부가 섭취한 알코올은 태반을 쉽게 통과하며 태아의 성장과 발육을 방해하여 기형을 일으킬 수 있다고 알려졌으며 이런 영아의 특징은 Jones 및 Smith(1973)는 태아알코올증후군(fetal alcohol syndrome)이라고 하였다. 태아알코올증후군은 중추신경계의 기능장애, 성장장애 및 특유한 용모 등의 증상을 나타내며 임상소견으로서는 중추신경계의 기능장애로 언어 및 인지능력의 저하를 비롯하여 운동조절의 장애, 근력저하, 평형유지 및 보행장애 등 일련의 소뇌의 기능과 관련된 질환이 나타난다. 한편, 태아알코올증후군을 나타낸 아동의 부검소견으로 소뇌의 발생장애(dysgenesis) 및 형성부전(hypoplasia)등이 있음을 지적하고 있다. 이에 저자는 알코올이 태아의 중추신경계에 미치는 영향을 관찰하고자 임신기와 수유기에 알코올을 투여한 모체에서 출생하고 성장한 신생 흰쥐의 소뇌피질의 과립층(granular layer) 및 분자층(molecular layer)에서 축삭종말(axon terminal)과 신경연접(synapses)의 미세구조적 변화를 전자현미경으로 관찰하고 영상분석기(Image analysis system)로 계측 분석하여 다음과 같은 결과를 얻었기에 보고하는 바이다. 실험동물의 소뇌피질의 과립층 및 분자층 구역 모두에서 축삭종말의 크기 및 연접치밀질의 길이가 감소하는 경향이였다. 특히 축삭종말의 크기 감소보다는 연접치밀질의 길이 감소가 더욱 현저하였다. 에틸알코올(10%)에 노출된 군과 포도주(알코올 12%)에 노출된 군 사이에는 유의한 차이가 없었다. 이상과 같은 결과로 보아 알코올은 태아의 중추신경계 중 소뇌피질 신경세포의 성장 및 분화에 영향을 미치는 것을 알 수 있었고 특히 신경세포의 성장보다는 신경연접의 분화에 더 큰 영향을 미친다고 추측되었다. 그래서 저자는 미세구조적 형태 변화가 소뇌의 기능장애의 원인이 되는 것이라고 생각하였다. ; The ingestion of alcohol by pregnant women is associated with central-nervous-system dysfunctions in offsprings including ataxia, poor coordination, kinetic tremors and balance and gait abnormalities. The purpose of this study was to observe the effects of maternal drinking of alcohol during pregnancy and lactating periods on the structures of synapses in the cerebellar cortex of neonatal rats. Control group consisted of neonatal rats whose mothers received standard chow and water. The subjects of experimental group were neonatal rats whose mothers ingested 10% ethyl alcohol or wine(alcohol 12%) during pregnancy and lactating periods. Quantitative analysis of the ultrastructural changes of synapses in both granular and molecular layer of the cerebellar cortex was carried out using image analysis system. The results were as follows: The size of axon terminal and the length of synaptic thickening of axodendritic synapses decreased significantly in the granular and molecular layer of all experimental groups. The decrease of length of synaptic thickening were more evident than that of size of axon terminal. There was no significant differences between ethyl alcohol group and wine group. These findings suggest that the exposure to alcohol during fetal and lactating periods disturbs the growth and differentiation of neurons in the cerebellar cortex in the neonatal rat and the effect of alcohol on the synaptogenesis is more evident than on the growth of neurons. It is possible that the altered ultrastructural patterns of neuron seen in ethanol toxicity may be one of the causative factors in cerebellar dysfunction.논문개요 ------------------------------------------------------------- ⅵ Ⅰ. 서론 ------------------------------------------------------------- 1 Ⅱ. 실험재료 및 방법 ------------------------------------------------- 4 A. 실험동물 --------------------------------------------------------- 4 1. 어미 흰쥐 ------------------------------------------------------- 4 2. 신생 흰쥐 ------------------------------------------------------- 4 B. 조직표본 --------------------------------------------------------- 5 C. 표본관찰 --------------------------------------------------------- 6 Ⅲ. 관찰결과 --------------------------------------------------------- 7 A. 사료 및 알코올 섭취량 -------------------------------------------- 7 B. 전자현미경적 관찰 ------------------------------------------------ 7 1. 소뇌피질 과립층의 소견 ------------------------------------------ 8 2. 소뇌피질 분자층의 소견 ------------------------------------------ 10 Ⅳ. 고찰 ------------------------------------------------------------- 13 Ⅴ. 결론 ------------------------------------------------------------- 18 참고문헌 ------------------------------------------------------------- 19 사진부록 ------------------------------------------------------------- 25 영문초록 ------------------------------------------------------------- 3

Recent epidemiology of Streptococcus pneumoniae in nasopharynxes of Korean children with acute otitis media

Background: This prospective study was performed to evaluate serotype distribution, multilocus sequence typing, and antibiotic susceptibility of Streptococcus pneumoniae identified in Korean children with acute otitis media (AOM) after the introduction of a 7-valent pneumococcal conjugate vaccine (PCV7). Methods: Nasopharyngeal aspirates were collected from children diagnosed with AOM in seven hospitals in Korea. The bacteria identified in these samples and the serotypes, sequence types (STs), and antibiotic susceptibilities of S. pneumoniae isolates were evaluated. Results: A total of 390 children were enrolled, and bacteria were identified in 376 (96.4%) children. S. pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were identified in 155 (39.7%), 127 (32.6%) and 86 (22.1%) children, respectively. Serotype 19A (22.4%) was the most common S. pneumoniae serotype, with serogroups 11 (14.7%) and 15 (13.5%) following. ST320 (23.5%) was the most common ST; ST166 (17.0%) and ST83 (8.5%) followed. The overall susceptibility rates of S. pneumoniae to oral penicillin V and amoxicillin/clavulanate were 2.6% and 53.2%, respectively. The susceptibility rate to cefditoren was 91.0%; however, the rates for other cephalosporins were less than 10.0%. Compared with other serogroups, S. pneumoniae serogroups 19, 11, and 15 showed significantly lower susceptibility rates to all the antibiotics tested. Conclusion: S. pneumoniae serotype 19A, serogroups 11 and 15 were the major nasopharyngeal-colonizing bacteria in Korean children with AOM after the introduction of PCV7. These relatively prevalent serotype/serogroups showed lower antibiotic susceptibility rates. (C) 2016 Published by Elsevier Ltd on behalf of Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases

(A) clinical survey of infective endocarditis

의학과/석사[한글] 감염성심내막염은 1885년 Rokitansky에 이해 처음으로 보고된 이래 많은 연구 발달이 이루어져 왔으며, 최근 초음파심음향도를 이용한 증식성병변의 높은 관찰률로 그 진단 및 치료, 예후판정에 많은 도움을 받게 되었다(고등, 1981, dillon, 1977, Pringle등, 1982 , Rubenson등, 1981). 그러나 우리나라에서는 감염성 심내막염에 대한 단편적인 연구나(고등, 1981, 장등, 1975). 증례보고뿐인(차등, 1958) 실정이다. 이에 저자는 1975년 1월부터 1984년 2월까지 약 10년간 연세의료원 소아과 및 내과에 입원하여 감염성심내막염으로 치료받았던 87례를 대상으로 임상적 관찰을 하여 다음과 같은 결론을 얻었다. 1. 평균연령은 24.8세였고 남녀비는 1.49대 1 이었으며 15세이하의 소아연령은 23명으로 26.4%였다. 2. 연령별 발생빈도는 커다란 증가는 보이지 않았으며, 같은 기간중 입원환자 2,500명당 1명의 비유로 발생하였다. 3. 기존심질환은 류마트성심질환이 52.3%로 가장 많았으며, 선천성 심질환이 39.7% 기존심질환이 없던 경우가 8%였으며, 이전에 심내막염을 앓은 경우가 4.6%, 심장판막대치술 후 발병한 예는 전체의 3.4%였다. 4. 입원당시의 임상증세중 가장 많았던 것은 발열로서 73.6%에서 있었고, 심부전증상, 심잡음의 순이었고, 검사소견중 혈액배양검상 양성률은 75.9%, 그리고 빈혈, C-양성반응, 혈뇨의 순이었다. 5. 혈액배양검사에서 양성을 보인 예중에서 가장 많은 균은 녹색연쇄상구균으로서 42.4%였고, 황색, 표피포도상구균과 함께 총 양성례의 71.2%로 차지하였으며, 혈액배양 양성 및 음성에 따른 합병증의 빈도는 큰 차이가 없었다. 6. 분리된 균주의 항생제에 대한 감수성 검사 결과, 녹색연쇄상구균은 테트라사이클린을 제외한 거의 모든 항생제에 예민했으며, D군 연쇄상구균은 클로람페니콜과 세팔로스포린에만 예민했고, 황색포도상구균은 클로람페니콜, 클록사실린과 세팔로스포린에 예민했으며 거의 모든 페니실린에 내성을 가지고 있었고, 표피포도상구균은 세팔로스포린에 전례가 예민했고, 클록사실린에는 75%가 예민했으며, 역시 페니실린에는 거의 모든 내성을 가지고 있었다. 7. 초음파심음향도를 실시한 55례중 58.2%인 32례에서 증식성병변이 관찰되었으며, 대동맥판에서만 관찰된 경우가 가장 많았고, 각 심질환에 있어서의 증식성병변의 위치는 주로 기존의 병변이 있던 부위에 존재하였다. 증식성병변의 유무에 따른 합병증의 빈도는 사망률에 있어서만, 증식성병변이 있던 경우가 없던 경우에 비해 3배 가량 높았다. 8. 전색증은 29.9%에서 발생하였는데, 그 위치는 뇌가 전체의 63%를 차지해서 가장 많았다. 9. 4-6주동안 입원하여 충분한 기간동안 항생제 치료를 받은 예는 40례로서 43.7%였으며, 치료에 의해 1주이내에 열이 떨어진 예는 입원당시 발열에 있는 환자의 48.5%였다. 10. 연령 및 성별에 따른 사망률의 남녀비는 1대 1.4였고, 1례를 제외하고는 모두 15세 이상의 성인들이었으며, 사망원인은 뇌전색증에 의한 것이 33.3%로 가장 많았고, 울혈성심부전에 의한 것이 25%였다. 11. 치료성적은 회복률이 69.0%, 사망률은 13.8%였으나, 환자의 사정으로 퇴원한 예가 많아서 정확한 치료효과를 판정하기가 어려웠다. [영문] After the first report on Infective Endocarditis by Rokitansky in 1885, much research was spent on the subject. Nowadays by use of Echocardiography, there has been a high discovery rate of vegetation, and thus made it more valuable in diagnosis., treatment, and the evaluation of prognosis. However is Korea, there have been only a few case reports and even fewer studies on infective endocarditis. This study is clinical analysis of 87 Infective Endocarditis cases, which were admitted and treated at the department of Pediatrics and Internal Medicine, diagnosed as Infective Endocarditis, during the period from January, 1975 to February, 1984. The results were as follows: 1. The mean age was 24.8 years and male to female ratio was 1.49:1. 2. Annual incidence showed no increment during this period and it was 1:2500. 3. Underlying heart diseases consisted of rheumatic heart diseases, 52.3%, congenital heart diseases, 39.7%, no underlying heart diseases, 8%, previous infective endocarditis, 4.6%, and prosthetic valve endocarditis, 3.4%. 4. Frequent clinical manifestations on admission were high fever, murmur, congestive heart failure and frequent laboratory findings were positive blood culture results, anemia, C-reactive protein positive, and hematuria. 5. Blood culture was positive in 75.9% and the most common infecting organism was alpha-Streptococcus, which consisted 42.4% of total positive cases, with S.aureus and S.epidermidis, these three organisms consisted of 71.2%. complications related to culture positivity showed no significant difference. 6. Antibiotics sensitivity of major isolated organisms were performed. alpha-Streptococcus was sensitive to almost all antibiotics except Tetracycline and group D-Streptococcus was sensitive to Chlorampenicol and Cephalosporin. S.aureus and S.epidermidis showed same results, which showed sensitivity to Chlorampenicol, Cephalosporin and Methicillin and resistence to Penicillin. 7. Echocardiography was performed in 55 cases and showed vegetation in 58.2%. Complications related to vegetation showed difference only in mortality rate, which was greater by 3 times in positive cases than in negative cases. 8. Embolism was complicated in 29.9% of cases, of which site was by far the most common to the brain, 63% of the cases embolism was found. 9. Sufficient duration of 4-6 weeks' hospitalization and antibiotics administration was done in 43.7% and the initial responce to therapy was noted in 48.5% of total febrile cases. 10. The mortality rate of the cases was 13.8% and male to female ratio was 1:1.4 and all but one case was beyond pediatric age. More frequent causes of death were embolism to the brain and congestive heart failure. 11. 69.0% of the patients recovered and 13.8% of the patients died. However, as many patients discharged against advice because of their economic or some other problem, precise therapeutic results of these cases could not be obtained.restrictio

The Immunogenicity and Safety of a Combined DTaP-IPV//Hib Vaccine Compared with Individual DTaP-IPV and Hib (PRP similar to T) Vaccines: A Randomized Clinical Trial in South Korean Infants

Recommended infant vaccination in Korea includes DTaP-IPV and Hib vaccines administered as separate injections. In this randomized, open, controlled study we assessed the non-inferiority of immunogenicity of DTaP-IPV//Hib pentavalent combination vaccine (Pentaxim T) compared with licensed DTaP-IPV and Hib (PRP similar to T) vaccines. We enrolled 418 healthy Korean infants to receive either separate DTaP-IPV and Hib vaccines (n = 206) or the pentavalent DTaP-IPV//Hib (n = 208) vaccine at 2, 4, 6 months of age. Antibodies to all components were measured before the first vaccination and one month after the third, and safety was assessed after each vaccination including recording of reactions by parents. We confirmed the non-inferiority of DTaP-IPV//Hib compared with DTaP-IPV and Hib vaccines; 100% of both groups achieved seroprotection against D, T, IPV, and PRP similar to T, and 97.5%-99.0% demonstrated seroresponses to pertussis antigens. Antibody levels were similar in both groups, except for those to the Hib component, PRP similar to T. In separate and combined groups geometric mean concentrations of anti-PRP similar to T antibodies were 23.9 and 11.0 mu g/mL, respectively, but 98.3% and 97.4% had titers = 1 mu g/mL, indicative of long-term protection. All vaccines were well tolerated, with no vaccine-related serious adverse event. Both groups had similar safety profiles, but the combined vaccine group had fewer injection site reactions. The immunological non-inferiority and similar safety profile of DTaP-IPV//Hib vaccine to separate DTaP-IPV and Hib vaccines, with the advantage of fewer injections and injection site reactions, supports the licensure and incorporation of DTaPIPV//Hib into the Korean national vaccination schedule

Draft genome sequences of clinical isolates of serotype 6E Streptococcus pneumoniae from five Asian countries

Although serotype 6E Streptococcus pneumoniae consistently expresses capsules of either vaccine-serotype 6A or 6B, certain genetic variants of serotype 6E may evade vaccine induced immunity. Thus, draft genome sequences from five clinical isolates of serotype 6E from each of five different Asian countries have been generated to provide insight into the genomic diversity in serotype 6E strains. © 2017 Park et al

Mycological studies and treatment of tinea pedis with the thiocarbanilide (L-1)

의학과/박사[한글] Aminoglycoside 항생제의 일종인 gentamicin(GM)은 그람음성균 치료에 널리 사용되나 이 항생제를 장기간 사용시에는 부작용으로 신독성과 내이독성이 나타난다(Bonnet등, 1976;Gary등, 1976; Kaloyanides 및 Pastoriza-Munoz, 1980). 독성발생은 세포의 괴사 또는 막효소의 억제가 그 원인이 될 수 있다고 한다. 즉 GM은 guinea pig cochlea의 stria vascularis와 spiral ligament에 존재하는 총 ATPase활성도와 Na**+-K**+-ATPase의 활성도를 억제하며, 개의 신장의 Na**+-K**+-ATPase활성도도 neo mycin에 의해 억제되고 (Lipsky 및 Lietman, 1980), guinea pig의 신장 피질과 수질의 microsome 분획의 Na**+-K**+-ATPase 활성도도 aminoglycoside 항생제에 의해 현저히 억제되며(Chahwala 및 Harpur, 1982) 사람의 적혈구막에 존재하는 Ca**++-ATPase 활성도(박 등, 1986)와 Na**+-K**+-ATPase활성도(Chahwala및 Harper, 1982) 모두 GM에 의해 억제된다는 것이 보고되었다. 따라서 본 실험에서는 세포막의 Na**+-K**+-ATPase활성도를 억제하는 것으로 알려진 GM이 세포막을 경계로 Na**+과 K**+의 이동 및 적혈구막의 (3)**H-ouabain결합에 미치는 영향을 관찰하여 다음과 같은 결론을 얻었다. 1) GM은 적혈구막 소편의 막효소인 Na**+-K**+-ATPase의 활성도를 억제시켰으며, 그 억제효과는 GM의 농도에 비례하였다. 2) 적혈구막을 통한 능동적인 (22)**Na유출은 GM에 의해 억제되었으며 ouabain과 GM을 동시에 첨가시 각각의 약물을 단독으로 첨가시보다 억제효과가 더 크게 나타났다. 3) GM은 능동적인 (86)**Rb유입을 억제시켰으며, ouabain과 GM을 동시에 첨가하였을때 그 억제효과는 GM 단독첨가시와 유사하였다. 4) GM은 적혈구막에서 (3)**H-ouabain 결합을 증가시켰다. 이상의 성적으로 미루어 볼때 GM에 의한 능동적인 (22)**Na유출과 (86)**Rb유입의 억제는 막효소인 Na**+-K**+-ATPase 활성도의 감소와 적혈구막에서 (3)**H-ouabain 결합의 증가에 기인한다고 생각된다. [영문] Gentamicin(GM) is a polybasic, aminoglycoside antibiotic used frequently for the treatment of serious gram-negative infections. The major limiting factors in the clinical use of GM, as well as other aminoglycoside antibiotics are their nephrotoxicity and ototoxicity. The primary mechanism of cell injury in aminoglycoside toxicity appears to be the disruption of normal membrane function and the inhibition of Na**+-K**+-ATPase activity. There is both indirect and direct evidence which suggests that the effect of aminoglycoside antibiotics on Na**+-K**+-ATPase may explain, or contribute to, their toxicity. It has been shown that aminoglycoside reduce total ATPase activity (Kaku et al., 1973) and Na**+-K**+-ATPase activity(linuma et al., 1967) in the stria vascularis and spiral ligament of the guinea pig cochlea. Lipsky and Lietman(1980) demonstrated dose dependent inhibition of canine renal Na**+-K**+-ATPase by neomycin. Chahwala and Harper(1757) reported that aminoglycoside antibiotics inhibited the activity of Na**+-K**+-ATPase in microsomal fractions of the cortex and medulla of the guinea pig kidney, isolated rat renal tubule and human erythrocyte ghosts. The present investigation was undertaken to elucidate the mechanism of GM on human erythrocytes by examining its effect on Na**+-K**+-ATPase activity, active sodium and potassium transport across red blood cell and (3)**H-ouabain binding to red blood cell membranes. The results obtained are summarized as follows: 1) GM inhibited significantly both the activity of total ATPase and Na**+-K**+-ATPase at all concentrations tested. 2) GM inhibited active (22)**Na efflux across red blood cell. When ouabain is present, the rate of (22)**Na efflux was completely inhibited. When both GM and ouabain were added, the inhibitory effect of active (22)**Na efflux was more pronounced. 3) Active (86)**Rb influx was inhibited significantly by GM In the presence of ouabain, the rate of (86)**Rb influx is markedly inhibited. But (86)**Rb influx is not appreciably altered by the presence of both GM and ouabain. 4) In the presence of GM, (3)**H-ouabain binding to red blood cell membrane increased. From the above results, it may be concluded that the inhibition of active sodium and potassium transport across red blood cell by gentamicin appears to be due to the inhibition of Na**+-K**+-ATPase activity and an increase in ouabain binding to red blood cell membranes.restrictio

Etiology of invasive bacterial infections in immunocompetent children in Korea (1996-2005): A retrospective multicenter study

The purpose of this study was to identify the major etiological agents responsible for invasive bacterial infections in immunocompetent Korean children. We retrospectively surveyed invasive bacterial infections in immunocompetent children caused by eight major pediatric bacteria, namely Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species that were diagnosed at 18 university hospitals from 1996 to 2005. A total of 768 cases were identified. S. agalactiae (48.1%) and S. aureus (37.2%) were the most common pathogens in infants younger than 3 months. S. agalactiae was a common cause of meningitis (73.0%), bacteremia without localization (34.0%), and arthritis (50%) in this age group. S. pneumoniae (45.3%) and H. influenzae (20.4%) were common in children aged 3 months to 5 yr. S. pneumoniae was a common cause of meningitis (41.6%), bacteremia without localization (40.0%), and bacteremic pneumonia (74.1%) in this age group. S. aureus (50.6%), Salmonella species (16.9%), and S. pneumoniae (16.3%) were common in older children. A significant decline in H. influenzae infections over the last 10 yr was noted. S. agalactiae, S. pneumoniae, and S. aureus are important pathogens responsible for invasive bacterial infections in Korean children. © 2011 The Korean Academy of Medical Sciences

Impact of IgM Antibodies on Cross-Protection against Pneumococcal Serogroups 6 and 19 after Immunization with 7-Valent Pneumococcal Conjugate Vaccine in Children

Although it is well known that pneumococcal conjugate vaccines provide cross-protection against some vaccine-related serotypes, these mechanisms are still unclear. This study was performed to investigate the role of cross-protective IgM antibodies against vaccine-related serotypes 6A, 6C, and 19A induced in children aged 12-23 months after immunization with 7-valent pneumococcal conjugate vaccine (PCV7). We obtained serum samples from 18 Korean children aged 12-23 months after a PCV7 booster immunization. The serum IgG and IgM concentrations of serotypes 6B and 19F were measured by enzyme-linked immunosorbent assay (ELISA) in serum. The opsonic indices (OIs) against vaccine serotypes 6B and 19F and vaccine-related serotypes 6A, 6C, and 19A were determined by an opsonophagocytic killing assay (OPA) in IgM-depleted and control serum. Both IgG and IgM antibodies in ELISA and opsonic indices in OPA against serotypes 6B and 19F were demonstrated in the immune serum. IgM depletion decreased the OIs against vaccine serotypes 6B (geometric means of OIs (GMIs) of 3,009 vs. 1,396, 38% reduction) and 19F (1,117 vs. 750, 36% reduction). In addition, IgM depletion markedly decreased the OIs against vaccine-related serotypes 6A (GMIs of 961 vs. 329, 70% reduction), 6C (432 vs. 185, 72% reduction), and 19A (301 vs. 166, 58% reduction). The booster immunization PCV7 induced protective antibodies in the form of both IgG and IgM isotypes. IgM antibodies contributed to eliciting cross-protection against vaccine-related serotypes as well as against vaccine serotypes

Early Changes in the Serotype Distribution of Invasive Pneumococcal Isolates from Children after the Introduction of Extended-valent Pneumococcal Conjugate Vaccines in Korea, 2011-2013

This study was performed to measure early changes in the serotype distribution of pneumococci isolated from children with invasive disease during the 3-year period following the introduction of 10- and 13-valent pneumococcal conjugate vaccines (PCVs) in Korea. From January 2011 to December 2013 at 25 hospitals located throughout Korea, pneumococci were isolated among children who had invasive pneumococcal disease (IPD). Serotypes were determined using the Quellung reaction, and the change in serotype distribution was analyzed. Seventy-five cases of IPD were included. Eighty percent of patients were aged 3-59 months, and 32% had a comorbidity that increased the risk of pneumococcal infection. The most common serotypes were 19A (32.0%), 10A (8.0%), and 15C (6.7%). The PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, 23F, and 6A) accounted for 14.7% of the total isolates and the PCV13 minus PCV7 types (1, 3, 5, 7F, and 19A) accounted for 32.0% of the total isolates. Serotype 19A was the only serotype in the PCV13 minus PCV7 group. The proportion of serotype 19A showed decreasing tendency from 37.5% in 2011 to 22.2% in 2013 (P = 0.309), while the proportion of non-PCV13 types showed increasing tendency from 45.8% in 2011 to 72.2% in 2013 (P = 0.108). Shortly after the introduction of extended-valent PCVs in Korea, serotype 19A continued to be the most common serotype causing IPD in children. Subsequently, the proportion of 19A decreased, and non-vaccine serotypes emerged as an important cause of IPD. The impact of extended-valent vaccines must be continuously monitored